Caps lock to control: not accepted by Blender
Apparently, the KDE settings aren't as "low level" as Blender's input system. This command, however, is:

setxkbmap -option ctrl:nocaps


It also makes Caps Lock an additional Ctrl, but at such a low level that Blender understands it too.

Source: http://www.emacswiki.org/emacs/MovingTheCtrlKey